A liquid propane chamber 3.25 by 6.5 by 13 in., operating in a magnetic field of 22 000 gauss, is described. A simple compact dark‐field type of illumination is used; this is discussed. For personnel and equipment safety a secondary pressure vessel is incorporated in the design. Special reference is given to some of the construction and design problems.A brief summary of the operation of the propane chamber in the 6.2‐Bev neutron beam is given.